The detection of trace pollutants in biological materials, natural water, industrial waste, and air has become increasingly important. The currently available detection techniques for most toxic materials are quite complicated and require skilled operators. Under many circumstances the samples have to be pretreated, and the whole procedure is usually lengthy and not practical for routine analysis. We propose to evaluate and develop an enzyme sensor in which detection is based on inhibition of the enzyme. The enzyme inhibition technique can be used for detection of a variety toxic agents including inorganic materials such as heavy metals, toxic anions such as cyanide, and organic substances such as pesticides. The general objective is to reduce workplace and drinking water health hazards by developing a new technique, based on the enzyme inhibition effect, for the detection of toxic agents. The specific Phase I objective is to demonstrate the feasibility of detecting, through the inhibition mechanism, low level toxic substances with easy to use, disposable enzyme electrodes. The expected result is an enzyme inhibitor detector able to detect toxic substances. The two researchers submitting this proposal have collaborated successfully to develop prototype enzyme-based sensors which will be a crucial background for the research and development described in this proposal. Successful enzyme inhibitor detectors have huge commercial potential in many industrial processes such as a detector for cyanide in waste water from the electroplating and metal mining industries.